The present invention relates to an orifice plate for an ink jet print-head for ejecting drops of an ink, the orifice plate comprising an outer surface which has a wettability with the ink, and at least one orifice arranged in the outer surface, the orifice being configured for ejecting ink drops, each orifice having an edge, the edge defining a transition boundary between the orifice and the outer surface, the wettability of the outer surface being poor near the edge of the at least one orifice. The present invention also relates to a method for manufacturing such an orifice plate.
An orifice plate of this kind is known from U.S. Pat. No. 5,434,606. According to U.S. Pat. No. 5,434,606 an orifice plate comprises an outer surface and at least one orifice comprising an edge, wherein a portion of the outer surface near the edge is non-wetting. Thus accumulation of residual ink drops near the edge of the at least one orifice is prevented, which residual ink drops may otherwise disturb the trajectories of subsequent ink droplets, leading to a deterioration in the print quality. Residual ink drops which are larger than the width of the non-wetting region may experience a driving force to move towards regions of the outer surface that are wettable with the ink and will automatically flow away from the edges of the orifices towards those regions. However, residual ink drops which are smaller than the width of the non-wetting region will bead on the non-wetting portion of the outer surface and stay there.
The orifice plate disclosed in the cited reference has the disadvantage that a small residual drop (smaller than the width of the non-wetting region) that has landed near an edge of an orifice, may disturb the trajectories of multiple subsequent ejected ink drops.